Transversely or sidewardly extending, elongate headers of from about 12 feet to 30 feet and greater in length are commonly utilized on windrowing machines for cutting and windrowing crops such as cereal grains and other seed crops, as well as grasses. Historically, the headers rested on skid shoes which moved along the surface of a field or pasture, to position cutting apparatus of the header, such as an elongate sickle cutter bar or a row of disk cutters, close to the surface for cutting the stalks or stems of crops and grasses close to the surface.
More recently, it has become more desirable and customary to cut the stalks of crops higher than is possible with the header resting on skid shoes. Prior known models of windrowers used hydraulic cylinders to carry the header at the desired height with flotation springs carrying a major percentage of the header weight. Newer generations of windrowers use hydraulic cylinders and accumulators to lift the header and also provide header flotation when the header is lowered to the ground in a cutting mode. Such newer generation windrowers have been found to be efficient for cutting hay crops, but some have no provision for carrying the header above the ground while also providing a flotation capability. A flotation capability is desirable on a header carried off the ground to allow the header to be guided over obstacles and uneven ground without damaging the cutting apparatus of the header.
A windrower construction providing a float capability with the header supported above the ground is disclosed in Schmid et al. U.S. Pat. No. 5,983,615, issued Nov. 16, 1999 to Deere & Co. The Schmid et al. construction utilizes linkage arrangements in connection with opposite ends of a header of a windrower, supported by a transversely extended rock shaft rotated by a central lift cylinder, for providing a height setting capability, and float cylinders in connection with the respective linkage arrangements for providing a float capability. It appears that the Schmid et al. construction allows sideward tilting of the header as a result of contact with the ground or other obstacles. However, Schmid et al. does not appear to disclose a capability for setting or supporting the header at a sideward or transverse tilt. That is, no capability is disclosed for maintaining the sides or transverse ends of the header at different minimum heights in relation to the windrower or a surface therebelow, such as the surface of a field, pasture, or the like. Additionally, Schmid et al. does not disclose a capability for easily returning the header to a previously selected cut height and tilt after lifting of the header.
A lack of a settable sideward tilt capability has been found to be a shortcoming for several reasons, including that it does not allow for accommodating uneven terrains such as where one side of a swath of a field or pasture to be cut is higher than the other. It may also be desirable to leave stubble on a field or pasture cut at an angle so as to retain more driven snow for better moisture retention when the snow melts. Similarly, in some circumstances it can be desirable to have the capability to independently raise and lower the ends of a header to correct for undesired sideward or transverse tilt. And, in many instances, it is desirable to have the capability to easily return to an earlier selected cut height, and tilt, after lifting of the header.
Thus, what is sought is a header height control system and apparatus for a work machine such as an agricultural windrowing machine or a harvesting machine, which provides a height control capability in combination with a float capability and a sideward or transverse tilt capability, along with a return to previously selected cut height capability, and which otherwise overcomes one or more of the shortcomings and limitations set forth above.